The present invention relates to probes for a waveguide, and more particularly to two probes that are printed on a circuit board in two substantially rectangular patterns separately located outside a round pattern near a lateral and a lower or an upper side thereof, so that a sufficient cross-polarization isolation exists between the two probes for them to more effectively and stably receive electric waves without interfering-with each other.
FIG. 1 shows a conventional waveguide 10 that includes a cup-shaped tube portion 11, a body portion 12, a circuit board 13, and two probe pins 14, 15. The probe pins 14, 15 are spaced from and perpendicular to each other, so as to receive waves from different directions and then transmit the received waves as signals to the circuit board 13, at where the received signals are processed.
The probe pins 14, 15 for the conventional waveguide 10 have the following disadvantages:
1. The probe pins 14, 15 are three-dimensional members projected from inner surfaces of the waveguide 10, and are therefore easily broken due to unexpected collision or impact.
2. The probe pins 14, 15 are three-dimensional members projected from inner surfaces of the waveguide 10, and therefore occupy considerable space in the waveguide 10, preventing the waveguide 10 from a small volume.
3. The cup-shaped tube portion 11 must have extended length to accommodate the long probe pins 14, 15. For the purpose of eliminating the above-mentioned disadvantages in the conventional waveguide 10, the inventor of the present invention has developed a waveguide 20 having coplanar printed probes as shown in FIGS. 2, 3 and 4. As shown, the waveguide 20 includes a cup-shaped tube portion 21, a body portion 22 vertically connected to a rear side of the cup-shaped tube portion 21, and a circuit board 23 mounted on the body portion 22 and perpendicular to the tube portion 21. The circuit board 23 is provided thereon with a substantially round pattern 23a, as shown in FIG. 3. A probe 23b is provided on a right side of the round pattern 23a, and another probe 23c is provided in a substantially rectangular pattern 23f to a left side of the round pattern, so that the probes 23b and 23c are perpendicular to and spaced from each other by a predetermined distance to avoid interference between two electric waves in two directions perpendicular to each other. The cup-shaped tube portion 21 is provided at a position adjacent to the probe 23c with a guide slot 23d, so that electric waves in the direction of the guide slot 23d of the cup-shaped tube portion 21 can be effectively received by the probe 23c and converted into electronic signals.
An advantage of the above-mentioned waveguide 20 is that the provision of the printed patterns and the guide slot 23d allows the coplanar probes 23b and 23c to be spaced from each other by a predetermined distance, so that electric waves could be effectively processed without causing wave interference.
However, since the probe 23b is provided in the round pattern 23a, there is an insufficient cross-polarization isolation between the probe 23b and the probe 23c provided in the rectangular pattern 23f. When the cross-polarization isolation between the probe 23b and the probe 23c is improved, an even better signal processing ability of the waveguide could be obtained.
It is therefore tried by the inventor to develop an improved circuit pattern to enhance the signal receiving ability of the waveguide.
A primary object of the present invention is to provide two printed probes on a circuit board of a waveguide, such that a sufficient cross-polarization isolation exists between the two probes for them to effectively receive electric waves from different directions without interfering with each other.
To achieve the above and other objects, the two printed probes of the present invention are printed on one side of the circuit board opposite to a cup-shaped tube portion of the waveguide at positions perpendicular to and spaced from each other by a predetermined distance. The two probes are separately located in two rectangular patterns that are provided outside a round pattern on the circuit board. The two rectangular patterns are separately located at a lower or an upper side and to a lateral side of the round pattern and both have a feed opening provided at an edge adjacent to the round pattern. Thus, it is possible to obtain a good cross-polarization isolation between the two probes for them to effectively receive electric waves in different directions without interfering with each other.